High density multi-level recording for archival data preservation

Abstract

Archival data storage is predominantly based on magnetic tape technology. An alternative probe based multi-level recording scheme is proposed which specifically addresses the issue of long term data preservation. In a first step, the data are written as topographic relief in an organic resist. To achieve long term preservation, the relief structure is transferred in a Si based inorganic carrier by means of reactive ion etching. Thereby, the data are preserved as written in stone. Using 3-level logic, a storage density of 99 Gb/in2 is demonstrated and read-back of the data is accomplished with an error rate of 10−3 based on threshold detection. Exploiting etch anisotropy in layered substrates, logic levels can be physically separated from one another in different layers which enhances tamper resistance and also provides a means for heterogeneous storage concepts.

Tipping solutions: emerging 3D nano-fabrication/ -imaging technologies

“…The AFM scanning probe technique can be used both as material deposition and removal tool with nano-scale precision and resolution [128]. One particular implementation of scanning nanotip techniques is the thermal scanning probe lithography (t-SPL) [9][10][11]. The technique offers maskless direct writing and is based on decomposition of a resist [Polyphthalaldehyde (PPA)] into volatile monomers upon contact with a hot (~700°C) nano-sharp tip ( Figure 14A).…”

“…This "optical coating" [8] by deep-UV is expected to advance nanoscale lithographic fabrication. Another emerging nano-lithography technique reviewed here uses a heated atomic force microcopy (AFM) tip [9][10][11]. Its primary advantage is its ability to completely avoid ionization damage to substrates while offering a 10-nm resolution that is on par with conventional electron beam lithography (EBL).…”

Thermal probe nanolithography: in-situ inspection, high-speed, high-resolution, 3D

“…Also, first applications using 3D patterning in PPA have been shown: Patterning of removable, shape-matching traps enabled the placement of gold nano rods onto a substrate with an accuracy of 10 nm [12]. As follow-on from the original data storage application, multi-level data bits have been written and transferred into silicon for archival data preservation [13]. …”

“…This is of great importance as it enables the direct transfer of the written topography into the underlying substrate. For example, patterns written into PPA have been transferred into silicon using a single SF 6 -C 4 F 8 -RIE step [13]. The depth of the pattern is amplified by a factor of two in the etch process.…”

AFM Imaging?Reliable or Not?: Validation and Verification of Images in Atomic Force Microscopy

“…Note that it is possible to increase the areal density by encoding multiple bits at the same location using different heights in topography to indicate different bits. For example, in [17] high areal density is enabled by encoding multiple levels in the height of the topographic features. Here the problem becomes detection of the height level rather than a simple detection of presence or absence of the sample.…”